Python - Dictionary

dictionary.py

phone_book = {"Batman": 468426,
              "Cersei": 237734,
              "Ghostbusters": 44678}


# ************************
# Enumeration
# ************************
for k in phone_book: # give keys
  # Batman
  
for tuple in phone_book.items(): # give tuples
  # ('Batman', 468426)

# can be simplified to..
for k, v in phone_book.items(): # give key and value
  # Batman 468426

for index, key in enumerate(phone_book): # enumerate give index and key
  # 0 Batman
  
for index, (key, value) in enumerate(phone_book.items()): # index, key and value
  # 0 Batman 468426


# ************************
# Removing
# ************************
cersei = phone_book.pop("Cersei")


# ************************
# Merge Dicts
# ************************
second_phone_book = {"Catwoman": 67423}
phone_book.update(second_phone_book) # merged into first dict

phone_book = {**phone_book, **second_phone_book} # merged into first dict
new_phone_book = {**phone_book, **second_phone_book} # or into a new dict

# python 3.9 only
d1 |= d2
new_d = d1 | d2


# ************************
# Dictionary Comprehension
# ************************
phone_book = {"Batman": 468426,
              "Cersei": 237734,
              "Ghostbusters": 44678}

uppercased_and_strings_phonebooks = {k.upper(): str(v) for (k, v) in phone_book.items()}
# {'BATMAN': '468426', 'CERSEI': '468426', 'GHOSTBUSTERS': '44678'}



# ************************
# Conversions from other data structures
# ************************

star_wars_list = [ [1,"Anakin"], [2,"Darth Vader"], [3, 1000] ]
star_wars_tup = ( (1, "Anakin"), (2, "Darth Vader"), (3, 1000) )
star_wars_set = { (1, "Anakin"), (2, "Darth Vader"), (3, 1000) }

star_wars_dict = dict(star_wars_list)
star_wars_dict = dict(star_wars_tup)
star_wars_dict = dict(star_wars_set)
                      
# It works as long as there is a list of tuples, because key value is a tuple